WAMReservedLabel is an WAMCallPoint that is an address for a label. The label in question may be forward
referenced, so its address cannot be resolved until the label is encountered as code is generated. In the situation
that a forward reference to a label is encountered, a dummy invalid address can be substituted for the label, and the
offset at which that dummy address is written can be recorded. Once the label has been resolved to a valid address,
the dummy values can be re-visited and corrected. WAMReservedLabel is an WAMCallPoint that also maintains a list of
referenced from address to be corrected, once the label address is known.

An WAMReservedLabel is created with an entry point of -1, which means that it has not been resolved to a known
address yet. Once the entry point is set to a value other than -1, it is considered to have been resolved.